10 July 2012
Osram’s low-profile Mini Midled 850nm infrared LED claims highest radiant intensity of its size class
Osram Opto Semiconductors GmbH of Regensburg, Germany says that its new infrared Mini Midled is only 0.9mm high but produces a narrow and intense beam of infrared light. With radiant intensity of 60 milliwatts per steradian (mW/sr) at a drive current of 100mA, it is claimed to outperform other comparable devices. The low-profile surface-mountable emitter particularly suits proximity sensors in devices where space is limited and for light barriers.
Picture: Osram Mini Midled’s narrow intense light beams offer zero crosstalk, suiting light barriers and proximity sensors.
Osram Opto says that in many sensor applications it is not only the optical power of an emitter that is important but also whether the available light is widely spread or concentrated in a narrow high-power beam, characterized by the half-angle. The radiant intensity (in watts per steradian) indicates the optical power within a solid angle and hence defines the intensity of the emitted light beam.
The Mini Midled’s emission half-angle is just 17°, producing a narrow light beam and a radiant intensity of 60mW/sr at 100mA by focusing the light with a metalized reflector integrated into the device. The new infrared LED offers a high output despite its small dimensions of just 2.3mm x 1.95mm x 0.9mm.
The Mini Midled is the second SMT device from Osram Opto in MID (molded interconnected device) technology, following the 1.6mm-high Midled. Due to new package technologies, Osram has managed to reduce the total height of the new infrared emitter to less than 1mm, but the new device can still be processed in the usual way.
Small and powerful infrared diodes with a wavelength of 850nm, such as the low-profile narrow-beam Mini Midled, offer major benefits in applications where there is little space but where high radiant intensity is needed, says the firm. Typical applications include light barriers, smart phones and optical touch screens.
“The low-profile Mini Midled is particularly suitable as an emitter for proximity sensors in smart phones and similar devices because it takes up very little space and yet delivers high power,” says marketing manager Bianka Schnabel. “Thanks to its sophisticated design, it also considerably reduces optical crosstalk, so no optical shielding is required, which makes life easier for designers,” she adds.
Proximity sensors are a combination of an emitter and a detector. The emitter illuminates an approaching object, and the light reflected from the object is received by the detector. For proximity sensors to operate properly it is crucial that no light from the emitter reaches the detector directly (crosstalk). This is precisely what often happens with devices that are not equipped with a metalized reflector, notes Osram Opto. However, with the Mini Midled there is no need for shielding and the overall design is much simpler, the firm claims.
Also, the non-metalized surfaces are dark colored, so the Mini Midled can be mounted inconspicuously behind a smart-phone cover.